77 Corvette Air Conditioner Repair Help
I've got this older corvette and the air conditioner continually looses freon.My question is if I have to start replacing parts [compressor-dryer etc.] would it pay me to switch to the new freon ? I only ask because I don't know much about the new feron and want to be able to make an informed choice Any help would be appreciated
Answer:
It's a very simple matter to change most GM systems over to R-134a, which is the standard refrigerant used now in all automotive installations. You'll need to replace the compressor, if as you say it's failing. You'll also need to use the correct, ester oil in the system, and replace the receiver/dryer or accumulator. If your system uses an orifice tube you'll get best results if you replace the orifice tube with one that is callibrated for R-134a -- though this is not absolutely necessary. If your car has a VIR assembly, I'm not sure what the proper procedure is for that. Maybe someone else on this newsgroup could fill us all in on that. It would be a good idea to flush the system, especially if you may have metal filings in it from the compressor. This is especially true if your car uses the R4 (short, with body diameter larger than the size of the pulley), since they tend to do that. The A6 compressor (long, with smaller diameter body) is more reliable. Leakage is another matter. Any leak that you have with R-12 will be worse with R-134a, because the molecules are smaller. Since the leak may be from the compressor, it may be fixed automatically when you do the job. What I would probably do is to make a thorough leak test first, so that I could replace whatever hose or other part was necessary while I had the system down. If I failed to find the leak I would go ahead and do the conversion. Then I could afford to lose a little bit of the cheaper freon as I struggled with the leak problem. R-134a is harder to detect, though, so you need to use a recent-model, high quality leak detector. I would not recommend that you try to use some kind of oddball freon replacement. There are some on the market, but in my understanding they have some distinct disadvantages. One is that most mechanics do not have access to this product, limiting your service options and exposing you to the danger of accidentally mixing incompatible refrigerants in the system. Another is that these products have very specific service requirements, and failure to follow the correct procedures can even result in a hazardous condition. Since these procedures are not widely known, you cannot depend on most mechanics to use them. R-134a is cheap and available, and your car is one of the easier ones to retrofit. Good luck; it's getting hot out there.